Do Solar Panels Work on Cloudy Days?
The Great Kiwi Weather Dilemma
Let’s face it: New Zealand is beautiful, but we aren’t exactly the Sahara Desert.
Whether you’re dealing with Auckland’s four-seasons-in-one-day humidity, Wellington’s horizontal drizzle, or a grey, overcast winter afternoon in Southland, cloudy days are a regular part of life down here.
So, it’s a completely fair question to ask: Do solar panels actually work on cloudy days? Or do they just go to sleep the moment a cloud rolls over?
If you listen to some solar sales reps, they’ll make it sound like their panels have magical properties that can pull power out of a thunderstorm. If you listen to the skeptics on Facebook, they'll tell you solar is a waste of money if you don't live in sunny Nelson.
Let’s cut through the noise and look at the actual science, the real numbers, and what happens to your power production when the weather turns rubbish.
The Short Answer: Yes (Because of Physics, Not Magic)
The short answer is yes, solar panels absolutely work on cloudy days. Solar panels do not require direct, blinding sunshine to generate electricity. They run on daylight.
To be more specific, they generate power from visible light spectrums and ultraviolet (UV) rays. Even on a thick, gloomy, overcast day, UV light still penetrates the cloud cover. (If you’ve ever gotten sunburned at the beach on a grey, overcast day, you’ve experienced this firsthand).
If there is enough light for you to see your hand in front of your face, there is enough light for your solar panels to generate electricity.
The Real Numbers: What is the Cloudy Day Penalty?
While panels do work in the shade and under clouds, we have to be realistic: their output will drop. Depending on how thick and heavy the cloud cover is, you can expect your solar panels to produce:
Light Clouds/Haze: About 50% to 80% of their maximum rated capacity.
Heavy, Dark Overcast Clouds: About 10% to 25% of their maximum rated capacity.
So, if your system normally produces 4kW of power at noon on a clear summer day, it might drop to 1kW or 500W during a heavy winter storm.
That sounds like a massive drop—and it is. But here’s why it’s not the disaster you think it is.
We go into more detail on weather its worth saving power in a solar battery for use on cloudy days/nights in another blog post.
The Huge Regulatory Change That Makes Solar Easier Right Now
If you're worried about cloudy weather slowing down your returns, you'll be glad to hear that the government has made it significantly cheaper and faster to install solar panels to offset those losses.
In late 2025, nationwide building consent rules changed dramatically. Rooftop solar arrays up to 40 square metres per roof are now completely exempt from requiring building consent.
Since a typical residential system of 20 to 24 panels is only about 30 to 35 square metres, almost every standard home installation in NZ now bypasses the council altogether.
This saves homeowners$1,060 to $1,200 in upfront consent fees and chops weeks of bureaucratic waiting out of the process. You can go from quote to generating your own power on a cloudy day in record time.
Rain is Actually a Solar Panel's Best Friend
What usually comes with clouds? Rain. And rain is actually fantastic for your solar system.
Over time, solar panels collect dust, pollen, bird droppings, and salt spray (especially if you live near the coast). This fine layer of grime acts like a permanent, mini-cloud over your panels, slowly dragging down your efficiency by 5% to 10%.
Unless you fancy climbing up onto your roof with a bucket of soapy water and a squeegee every few months, you need a way to clean them.
Enter Mother Nature.
A good Kiwi downpour is the ultimate free maintenance service. It washes away all the dirt and debris, leaving your panels sparkling clean and ready to maximize generation the moment the sun breaks through again.
Of course, rain doesn’t always do a perfect job, and some maintience is required over time, which is why companies like Ecoshine solar are great for the performance and lifespan of your panels.
The German Paradox (Why Cloudy NZ is Perfect for Solar)
If you’re still worried that New Zealand is too cloudy for solar to make financial sense, consider this: Germany is one of the world leaders in solar energy.
Over 10% of Germany’s entire electricity grid is powered by solar.
Do you know what Germany’s climate is like? It’s notoriously cloudy, cold, and grey. Major German cities like Munich and Berlin get significantly less annual sunshine hours than Auckland, Hamilton, Wellington, Christchurch, and Dunedin.
If solar can make massive financial sense in a cold, cloudy European nation, it will absolutely crush it on your roof in New Zealand.
Don’t Buy the Sales Pitch. Get the Real Data.
Every solar company has a brochure claiming their panels are "the best in low-light conditions."
Don't buy the hype.
At Equity Solar Brokers, we don't guess how cloudy days will affect your investment. We use independent, localized NIWA weather data to model exactly how much sunshine—and cloud cover—your specific suburb gets over a 10-year average.
We design a system tailored to your local microclimate. Then, we act as your personal brokers, taking that design to the market to procure three highly competitive, transparent quotes from NZ's most trusted, pre-vetted solar installers.
No sales pressure. No fluffy marketing. Just smart design and sharp prices.
Ready to see how solar will perform on your roof—even when the clouds roll in?
Talk to our friendly solar brokers and get 3 Free Quotes.
